Floating roof tank sealing methods and apparatus

Abstract

A seal is attached to and curved around a floating roof of a storage tank for petroleum products or other liquid materials, to extend to an outer circumference at the tank wall. The curved seal is suspended at first suspension points on the seal spaced about the floating roof. These first suspension points are spaced from the mentioned outer circumference at the wall by a first distance greater than zero and from the floating roof at a second distance greater than such first distance. The curved seal is suspended at these first suspension points from a series of corresponding second suspension points spaced from the first suspension points by third distances. Each of the second suspension points is spaced from the tank wall by a fourth distance greater than zero and from a peripheral cylindrical reference surface about the floating roof by a fifth distance greater than the mentioned fourth distance. The lengths of the fourth and fifth distances are varied in response to fluctuations of the varying width between the floating roof and the tank wall. The ratio of the fourth width to the fifth width is maintained constant during fluctuations of the latter varying width.

We claim: 
     
       1. In a method of preventing vapor from escaping from a storage tank through an annular space of varying width between a floating roof in, and a wall of, said tank, the improvement comprising in combination the steps of: closing said annular space with a corresponding annular flexible seal extending in said tank from said floating roof to an outer circumference at said wall for a width larger than the largest extent of said varying width;   curving said seal around said floating roof and between said floating roof and said wall;   applying to the curved seal at intervals spaced about said floating roof a series of forces each acting on said curved seal at a first distance from said outer circumference at said wall and at a second distance from said floating roof greater than said first distance;   varying said forces in response to fluctuations of said varying width; and   reversing said forces by applying a lifting force in response to diminution of said varying width.   
     
     
       2. A method as claimed in claim 1, wherein: the curved seal is suspended with said forces at said intervals.   
     
     
       3. In a method of preventing vapor from escaping from a storage tank through an annular space of varying width between a floating roof in, and a wall of, said tank, the improvement comprising in combination the steps of: closing said annular space with a corresponding annular flexible seal extending in said tank from said floating roof to an outer circumference at said wall for a width larger than the largest extent of said varying width;   curving said seal around said floating roof and between said floating roof and said wall;   suspending the curved seal in said tank with a series of suspension devices coupled to said floating roof and riding along said wall; and   selectively lifting said suspension devices off said wall in response to diminution of said varying width.   
     
     
       4. A method as claimed in claim 3, including the step of: 
     
     
       coupling said curved seal to said suspension devices at locations spaced from said outer circumference at said wall. 
     
     
       5. A method as claimed in claim 3 or 4, wherein: said curved seal is flexibly coupled to said suspension devices.   
     
     
       6. Sealing apparatus for preventing vapor from escaping from a storage tank through an annular space of varying width between a floating roof in, and a wall of, said tank, the improvement comprising in combination: means for closing said annular space including a corresponding annular flexible seal of a width larger than the largest extent of said varying width;   means for curving said seal around said floating roof and between said floating roof and said wall, including means for mounting said seal of larger width on said floating roof to extend in said tank from said floating roof to an outer circumference at said wall; and   means for applying to the curved seal at intervals spaced about said floating roof a series of forces each acting on said curved seal at a first distance from said outer circumference at said wall and at a second distance from said floating roof greater than said first distance, said force applying means including means for varying said forces in response to fluctuations of said varying width;   said means for applying forces include means for suspending the curved seal at said intervals; and   said means for applying forces include lifting means for reversing the suspension of the curved seal by lifting the suspending means in response to diminution of said varying width.   
     
     
       7. Sealing apparatus for preventing vapor from escaping from a storage tank through an annular space of varying width between a floating roof in, and a wall of, said tank, the improvement comprising in combination: means for closing said annular space including a corresponding annular flexible seal of a width larger than the largest extent of said varying width;   means for curving said seal around said floating roof and between said floating roof and said wall, including means for mounting said seal of larger width on said floating roof to extend in said tank from said floating roof to an outer circumference at said wall;   means for suspending the curved seal in said tank including a series of suspension devices coupled to said floating roof and riding along said wall; and   means coupled to said curved seal for selectively lifting said suspension devices off said wall in response to diminution of said varying width.   
     
     
       8. Apparatus as claimed in claim 7, wherein: the suspending means and the lifting means are coupled to the curved seal at locations spaced from said outer circumference at said wall.   
     
     
       9. Apparatus as claimed in claim 7 or 8, wherein: the suspending means and the lifting means include flexible links connected to the curved seal at locations spaced from said outer circumference at said wall.   
     
     
       10. In a method of preventing vapor from escaping from a storage tank through an annular space of varying width between a floating roof in, and a wall of, said tank, the improvement comprising in combination the steps of: closing said annular space with a corresponding annular flexible seal extending in said tank from said floating roof to a circumference at said wall for a width larger than the largest extent of said varying width;   curving said seal around said floating roof and between said floating roof and said wall;   suspending the curved seal in said tank with a series of suspension devices coupled to said floating roof and riding along said wall; and   causing said curved seal to lift said suspension devices off said wall in response to diminution of said varying width.   
     
     
       11. A method as claimed in claim 10, including the steps of: coupling said seal to said suspension devices at curved portions of said seal at a distance from said circumference at said wall.   
     
     
       12. A method as claimed in claim 10, wherein: said seal is flexibly coupled to said suspension devices at curved portions of said seal.   
     
     
       13. Sealing apparatus for preventing vapor from escaping from a storage tank through an annular space of varying width between a floating roof in, and a wall of, said tank, the improvement comprising in combination: means for closing said annular space including a corresponding annular flexible seal of a width larger than the largest extent of said varying width;   means for curving said seal around said floating roof and between said floating roof and said wall, including means for mounting said seal of larger width on said floating roof to extend in said tank from said floating roof to a circumference at said wall;   means for suspending said curved seal in said tank including a series of suspension devices coupled to said floating roof and riding along said wall; and   means coupled to the curved seal for causing said curved seal to lift said suspension devices off said wall in response to diminution of said varying width.   
     
     
       14. Apparatus as claimed in claim 13, wherein: the suspending means and the lifting means are coupled to said seal at curved portions of said seal at a distance from said circumference.   
     
     
       15. Apparatus as claimed in claim 13, wherein: the suspending means and the lifting means include flexible links connected to said seal at curved portions of said seal at a distance from said circumference.